1. Field of the Invention
The invention relates to a fuel injection apparatus and a control method thereof.
2. Description of Related Art
In recent years, various measures to address aging variation in an opening/closing operation of a fuel injection valve (an injector) have been proposed. For example, in a fuel injection valve proposed in Japanese Patent Application Publication No. 2001-280189 (JP 2001-280189 A), in order to address variation in an injection amount characteristic caused by aging variation in a fuel injection valve that uses gas fuel or corrosive fuel, variation in an opening/closing delay of the fuel injection valve is detected and a fuel injection pulse width is corrected accordingly. In this fuel injection valve, an initially set injection amount is maintained by correcting the fuel injection pulse width.
Incidentally, one cause of aging variation in the fuel injection valve is condensation of an acidic component of gas remaining in a cylinder. When the acidic component condenses and adheres to a tip end portion of the injector, an injection hole portion provided in the tip end portion of the injector may corrode. When the injection hole portion corrodes, atomization of the fuel injected from the ignition hole portion may be affected, and as a result, smoke may be generated.
In the fuel injection valve disclosed in JP 2001-280189 A, however, the effect of injection hole corrosion caused by condensed water is not taken into consideration. More specifically, the injection hole starts to corrode by the condensed water from an injection hole outlet in the vicinity of a combustion chamber, and therefore substantially no variation is seen in the fuel injection amount. Hence, it is difficult to diagnose injection hole corrosion accurately simply by detecting the opening/closing delay.